1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method which process a substrate. Substrates to be processed include, for example, semiconductor wafers, liquid crystal display device substrates, plasma display substrates, FED (Field Emission Display) substrates, optical disk substrates, magnetic disk substrates, magneto-optical disk substrates, photomask substrates, ceramic substrates, and photovoltaic cell substrates.
2. Description of Related Art
Japanese Patent Application Publication No. 2006-344907 discloses a substrate processing apparatus of a single substrate processing type that processes substrates, such as semiconductor wafers, one by one. The substrate processing apparatus includes a spin chuck that rotates a substrate while horizontally holding the substrate, a chamber that contains the spin chuck, and a nozzle that discharges a high-temperature chemical liquid higher in temperature than room temperature toward the upper surface of the substrate held by the spin chuck. When a chemical liquid valve is opened, the chemical liquid is supplied from a chemical liquid supply passage to the nozzle, and is discharged from a discharge port of the nozzle.
In the substrate processing apparatus, when the chemical liquid valve is closed, the supply of the chemical liquid to a flow passage leading from the chemical liquid valve to the discharge port of the nozzle is stopped. Therefore, the temperatures of a piping etc., that define the flow passage fall. Thereafter, when the chemical liquid valve is opened to discharge the high-temperature chemical liquid, the piping etc., are warmed with the chemical liquid. The temperature of the chemical liquid discharged from the nozzle rises until the temperatures of the piping etc., are stabilized.
When a plurality of substrates are processed in the same chamber, the processing quality of a first substrate is likely to differ from that of each substrate subsequent to the first substrate. If a pre-dispensing step of causing the nozzle to discharge the chemical liquid is performed before supplying the chemical liquid to a substrate to be processed, it is possible to stabilize the temperature of the chemical liquid to be supplied to the substrate, and it is possible to improve the uniformity in processing quality.
However, in conventional substrate processing apparatuses, an actual temperature of the chemical liquid discharged from the nozzle in the pre-dispensing step is uncertain, and therefore there is a need to set the discharge time of the chemical liquid longer than a period of time required to allow the temperature of the chemical liquid to become stable. If so, an essentially needless chemical liquid will be discharged, and therefore throughput (i.e., the number of substrates to be processed per unit time) will fall, and chemical liquid consumption will increase.
This problem can be caused not only in a case in which the temperature of a processing liquid is higher than room temperature but also in a case in which the temperature of a processing liquid is lower than room temperature. Additionally, this problem can be caused not only in a case in which a substrate is processed by a high-temperature or low-temperature processing liquid but also in a case in which a substrate is processed by a high-temperature or low-temperature processing gas.